“World News Tonight” co-anchor Elizabeth Vargas, who’ll take a maternity break at the end of the summer, is having a boy. It’ll be the second son for Vargas and husband Mark Cohn (son Zachary is 3).

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Looks like CBS has a hit on its hands with “The Unit,” which snared 18 million viewers Tuesday, retaining nearly all its viewership from Week One (shows usually average a 20 percent dropoff in the second week). The show, starring Dennis Haysbert, Scott Foley and Regina Taylor, also finished second in adults 18-49.

A repeat of “Law & Order: SVU,” meanwhile, finished first at 10 p.m. in viewers (11.2 million) and adults 18-49.

* “She’s The Man” star Amanda Bynes to “Access Hollywood”: “I’m so happy as a person that I don’t like to go to parties . . . and I prefer to be with my family.”

* The most obnoxious press release in history: Universal’s ginormous “King Kong”-on- DVD spiel, so big it arrived in a tube.

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* Text messaging is turning out to be a serious profit center for “American Idol.” Cingular Wireless, which has the exclusive rights to “Idol” text voting, recorded 41.5 million calls last season. At current rates, that translates to $4.15 million.

* Now we’re finding out why “Las Vegas” (Vanessa Marcil, left) was moved to Friday nights. Seems NBC wouldn’t be able to promo it next year during Sunday night football. “Vegas” is about gambling and NFL rules prohibit that.